package priv.pront.code.robot.roboCom_uni;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;

/**
 * @Description:
 * @Author: pront
 * @Time:2023-06-29 14:54
 */
public class P1163_银行贷款 {
    static StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static int a, b, c;
    public static void main(String[] args) throws IOException {
        st.nextToken();
        a = (int) st.nval;
        st.nextToken();
        b = (int) st.nval;
        st.nextToken();
        c = (int) st.nval;
        double l = 0, r = 1000, mid = 0;
        while (l < r - 0.0001) {
            mid = (l + r) / 2;
            double w = a;
            for (int i = 0; i < c; ++i) w = w - b + w * (mid / 100);
            if (w > 0.0001) r = mid;
            else l = mid;
        }
        String ans = String.format("%.1f", l);
        System.out.println(ans);

    }
}
